The invention relates to a tensioning device, in particular for a machine vice, with a base body, with a stationary jaw arranged thereon and with a movable jaw opposite this for whose adjustment there is provided a tension rod, wherein the tension rod comprises a support bearing via which the movable jaw is supported by way of a compression rod.
A tensioning device according to this type is known from the German patent document DE-C1 40 18 284.
The patent document describes a machine vice with a force amplifier. The movable jaw is moved to the subject to be tensioned by rotating a sleeve on which there is located an outer thread.
A coaxially mounted spindle actuates subsequently a force amplifier which creates the necessary tensioning force between the stationary and movable jaw.
The movable jaw cooperates with the sleeve as a spindle-nut drive. With this the movable jaw is the nut and the sleeve is the spindle.
With the machining of the subject any occuring swarf may fall downwards onto the thread of the sleeve and thus penetrate into the gap between the movable jaw and the thread of the sleeve. The result of this is an increased wear as well as disturbances on adjusting the movable jaw. Furthermore the application of the movable jaw onto the subject demands a disadvantageous, great time expense since for tensioning firstly by way of rotating the sleeve the movable jaw must be traversed onto the subject.
It is the object of the invention to specify a tensioning device which permits a quick tensioning also of differently dimensioned subjects and furthermore offers a largest possible protection from contamination of the functional parts.
This object is achieved with a tensioning device of the known type in that the movable jaw is designed lockable at various distances to the stationary jaw with the compression rod, preferably lockable by way of a clamping body. The locking may again be easily released and after a subject change may again be locked in a new position. By way of a subsequent rotation of the tension rod which with its thread for example engages into a nut of the base body, the subject may be tensioned in the shortest of times. The locking may also advantageously be effected by clamping bodies which are formed in the manner of a free-wheel. By way of a suitable actuating device the position of the clamping body may be changed such that the locking of the movable jaw may be released again in order to change the distance to the stationary jaw arbitrarily.
Advantageously the locking may also be formed with a positive fit when the compression rod comprises catching surfaces into which counter-surfaces of the movable jaw or its movable carrier element are engagingly arranged. The movable jaw after releasing the catching may be easily pushed onto the subject so that there is given a quick adjustability of the jaw.
After a renewed catching the jaw may be finely adjusted and the necessary tensioning pressure may be mustered by rotating the tension rod or by actuation of a suitable hydraulic or pneumatic cylinder.
The catching of the functional parts is effected between the movable jaw and the compression rod or between its movable transport element and the compression rod.
The compression rod at the same time essentially retains its relative position to the tension rod. For the quick adjusting thus the movable jaw or its movable transport element is adjusted relative to the compression rod.
The compression rod may simultaneously protect the tension rod from contamination when the compression rod is formed as a sleeve which at least partly envelops the tension rod. The tension and compression rod are at the same time coaxially mounted.
The operation of the tensioning device is simplified in that for the sleeve there is provided a tensioning position in which the movable jaw or its carrier element is supported via the sleeve on the tension rod, and there is provided an adjusting position in which the movable jaw is designed displaceable relative to the base body. At a certain angular position there arises a frictional connection, prefereably also a positive-fit connection, between the sleeve and the movable jaw or its carrier element.
In another angular position into which the sleeve may be brought by rotation about its longitudinal axis, this frictional connection, preferably also positive-fit connection is released so that the movable jaw or its carrier element may be displaced relative to the base body.
The frictional and positive-fit connection of the sleeve and the jaw may be achieved in that on the sleeve there is provided at least one support surface as a catch surface which is preferably formed as a web.
If the movable jaw or its movable carrier element comprises channels adapted to the web then the force transmission from the jaw or its movable carrier element is effected via the channels onto the web of the sleeve.
The selective switching of a possible frictional connection or the releasing of the frictional connection is with regard to design made particularly simply in that the collar is only provided at one part of the sleeve circumference.
By rotating the collar the webs may rise out of the channels since the carrier part below comprises a longitudinal slot which is wider than the side surfaces of the web.
With this rotation any swarf located on the sleeve is moved from the spindle upper side into the inner space of the base body, thus away from the spindle.
The sleeve is simultaneously advantageously guided in the movable jaw or in its carrier parts in that the recess below comprises a longitudinal slot which is wider than the web of the sleeve.
A particularly comfortable adjustment in order to bring the sleeve out of the tensioning position into the movable adjusting position may be achieved when the sleeve is rotatably mounted about its longitudinal axis.
The installation of the movable jaw or its movable carrier element and the manufacture of the engagement of the webs into the channel profile is achieved by way of the measure that the movable carrier element has a symmetrical channel profile for the engagement of the webs of the sleeve.
The tensioning width may be advantageously changed by way of a 180xc2x0 rotated installation of the movable jaw on its carrier element. For this however the carrier element is provided with a fastening profile for the movable jaw, which itself is formed non-symmetrically to the channel profile. By rotating the movable carrier element together with the jaw by 180 degrees in the horizontal, the tensioning range of the tensioning device may be comfortably adjusted. For similar tensioning regions by way of this the constructional length of the base body may be kept shorter.
A sufficiently high tensioning force for many cases may be achieved when the tension rod is formed as a part of a spindle-nut drive for adjusting the movable jaw, preferably for this comprises an outer thread which is formed engaging into a nut of the stationary jaw or of the base body.
By way of the fact that the nut of the spindle-nut drive is formed of plastic, in many cases one may do away with hydraulic, pneumatic or mechanical force amplifiers.
Advantageously the design manner of the tensioning device however also permits the provision of a hydraulic, pneumatic or mechanical force amplifier, preferably acting on the spindle.
In practice one embodiment form has shown to be particularly successful in which the sleeve has at least one angular position, which is formed catchable, preferably with a friction fit. On operation the thus locked angular position may be differentiated from the position in which the jaw is freely displaceable.
The mustered tensioning force may advantageously be easily controlled when a free end of the spindle comprises a square socket which is formed for receiving a standard torque key. Since such a torque key is present anyway on most shop floors by way of the combination of the quick-adjustment with the spindle-nut drive of the tension rod the tensioning force may be mustered in a comfortable and directed manner. Particular further measures are not required.
Advantageously it is envisaged that at least one jaw, preferably the stationary jaw comprises a holding device, in particular a holding edge. By way of this it is possible to grip the tensioning device at the holding device and to transport it.
The safety on cleaning the tensioning device is advantageously increased in that at least one jaw comprises a cover plate which preferably is fastened with a screw. In the heads of the fastening screws there accumulates swarf which then on blowing out of the tensioning device may injure the operator. By way of the use of a cover plate the fastening screws are covered so that here no dirt may accumulate. Preferably the cover plate is fastened with only one centric screw.
Further dirt accumulation may be advantageously avoided in that the groove is not designed continuous.
The rotating of the sleeve is simplified in that the grip is at least partly knurled. The knurling has furthermore the advantage that it forms a marking. The left end of the knurling before actuation of the tension rod bears flush on the base body. Without the knurling there exists the danger that the operator does not notice that the spindle-nut drive is overwound which has the result that the tension rod is pressed against the lid of the base body. By way of the knurling the operator may much better estimate how much distance there is still present between the lid and the tension rod.
It is advantageously envisaged that in the grip there is incorporated a marking, preferably a flute. This flute is in the basic condition the distance to the base body about which the tension rod may be maximally rotated. If the marking after actuation of the tension rod bears flush on the base body a further rotation of the tension rod need not take place.
One advantageous embodiment of the invention envisages that on the left end of the nut there are arranged disk springs. The tension rod on actuation is pressed against these springs by which means a pressure is exerted onto the tension rod. This pressure build-up is an additional precautionary measure which is to remind the operator that the tension rod is no longer distanced far from the maximal abutment.
By way of the fact that the movable jaw comprises grip windows the displacement of the jaw by hand is simplified.
In order to prevent an excessive force build-up on the subject it is advantageously envisaged that the nut is formed as a sliding clutch. If the build-up tensioning force exceeds a maximum value, the nut slides through, by which means a force limitation takes place.
A constructional simple measure in the design of the sliding clutch lies in setting the nut between two O-rings. The pressing force is matched such that on exceeding the maximal allowable tensioning force a sliding-through of the nut is effected.
The stability of the tensioning device is increased in that the nut is formed of metal, preferably bronze or brass.
The invention is described in a preferred embodiment example by way of example with reference to the drawings, wherein further advantages of the invention may be deduced from the details of the drawings. Parts which with regard to function are the same are provided with the same reference numerals.